Skier-triggered wind slab avalanche on Stevens

Toured up into Stevens east bowl this morning. Snow was very wet below treeline from recent rain. It was much windier than expected up high with gale force winds and massive snow transport south to north along all exposed ridglines above.  SIgnificant snow transport was also ongoing at lower elevations as well, within the relatively protected bowl and trees, and we noted widespread wind effect and active snow transport and deposition throughout elevations on multiple terrain features at mid elevations above treeline. Visibility was worsening and we decided to turn around prior to reaching the climb to the ridgeline.

On the way out of the east bowl, one member of the party rounded the corner about mid way up the small slope on skiers right as you exit the bowl (those familier will know this slope as a commonly wind-loaded test slope which often has wind slab formation on it-yes, the one youre always tempted to ski cut to see if it will break!). 

As the skier traversed downward away from and off of the slope, it fractured, and propogated all the way across the slope, probably a few hundred feet. The original crown varied from thin, ~2-3", to around 4-6" at its thickest. The slab slid the entire length of the slope and beyond, runing for ~100 feet at its longest.  It also stepped down and triggered what appeared to be another wind slab underneath it.  The surface bed was not faceted, but was soft unconsolidated old snow upon which the freash wind slab had been recently depositied. All told it was a significant amount of snow entrained with fracture blocks in the debris as thick as 10".

The skiier initially got his feet caught up in the thick fracture blocks and slide snow and then was carried about 30-40ft by the slide in a sitting postion and was partially buried in this position with airway and torso above the snow.  The skier was able to stand up and self-extricate without assistance and suffered no injuries and skiied out on their own. At the bottom of the slide, an impressive amount of snow had been entrained and probably could've burried a victim if circumstances had been unlucky.